This invention relates to a luminous signalling device. More particularly, the invention refers to a luminous signalling plate, particularly useful for the installation on the deck of ships.
It is an object of this invention, to provide a light source adapted to signal the outline of the deck and/or operatively important zones on this latter, such as the flying-on-deck areas of airplane or copter carriers, which is distinguished from the ones known. The device of the invention has better operating features, reduced overall dimensions, and higher reliability features, even in the most severe operating conditions.
The light sources heretofore known are formed by one or more filament lamps, positioned, together with their lamp holders, in a housing equipped with a transparent screen. Such a housing is of somewhat great overall dimensions, and entails some problems in respect of the dissipation of the heat produced by the lamps, since the housing must be hermetically tight.
Moreover, the filament lamps have a high electrical input, a limited average life, and a low resistance to shocks and vibrations, except in the case that expensive and complicated anti-shock and anti-vibration devices are provided.
According to the invention, the light source is formed by one or more electroluminescent units, mounted within a support having suitable features, and protected by an upper transparent screen.
The electroluminescent units, already known, for example, from U.S. Pat. Nos. 3,353,050 and 3,354,554, consist in a conductive sheet on which a layer of phosphor is spread, which in turn is coated with a transparent conductive layer. The input voltage is applied between the transparent coating and the conductive sheet, so that the electroluminescence of the phosphor takes place.
Such transparent coating and conductive sheet have a combined thickness of the order of one millimeter, do not develop heat ("cold light"), have a very low electrical power consumption (about 0.1 mA/cm max), have a life of several thousands of hours, and are intrinsically shock and vibration resistant.
The electroluminescent units, properly fed, show a lighting power sufficient to render the same visible at a distance of the order of one thousand meters in standard atmosphere, and the light emitted therefrom may be colored in green, orange, blue or white.
The invention will be now described with reference to the accompanying drawings which show by way of a non-limiting example a preferred embodiment of the invention itself.